The Weyl anomaly has had a very rich history dating back almost five decadesFor a wonderful memoir of the development of Weyl anomaly, the reader is pointed to [1]}. and has found applications in diverse fields such as quantum gravity, black hole physics, inflationary cosmology, string theory and statistical physics. We are now concerned about the form of Weyl symmetry and Weyl anomaly in 2d BMS-invariant field theories, which as stated above, would be useful for understanding aspects of holography in asymptotically flat 3d spacetime, or for tensionless string theories. It is possible that this construction would find similar applications in logarithmic corrections to entropies of Flat space cosmologies in 3d [2]}, aspects of inflationary cosmology, and even statistical physics. Our constructions of the Weyl symmetry and its anomaly in this paper would be purely from the field theoretic side. One can envision that a holographic computation in flat spacetimes, following the lead of [3]} and with suitable modifications for the asymptotically flat case, would reproduce the answers we obtain in this paper.
